[Qemu-devel] [PATCH v1 1/3] e1000: emulate auto-negotiation during external link status change

["Gabriel L. Somlo" <gsomlo@gmail.com>]

This patch emulates auto-negotiation when the network link status
is modified externally (i.e. via "set_link <id> off/on").

Also, a couple of cleanup items regarding the PHY status register:
  - unset AUTONEG_COMPLETE during link_down()
  - set AUTONEG_COMPLETE during autoneg_timer() only if we actually
    brought the link up.

Signed-off-by: Gabriel Somlo <somlo@cmu.edu>
---
 hw/net/e1000.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index 57bdffd..f0070ca 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -175,6 +175,7 @@ e1000_link_down(E1000State *s)
 {
     s->mac_reg[STATUS] &= ~E1000_STATUS_LU;
     s->phy_reg[PHY_STATUS] &= ~MII_SR_LINK_STATUS;
+    s->phy_reg[PHY_STATUS] &= ~MII_SR_AUTONEG_COMPLETE;
 }
 
 static void
@@ -197,7 +198,6 @@ set_phy_ctrl(E1000State *s, int index, uint16_t val)
     }
     if ((val & MII_CR_AUTO_NEG_EN) && (val & MII_CR_RESTART_AUTO_NEG)) {
         e1000_link_down(s);
-        s->phy_reg[PHY_STATUS] &= ~MII_SR_AUTONEG_COMPLETE;
         DBGOUT(PHY, "Start link auto negotiation\n");
         timer_mod(s->autoneg_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 500);
     }
@@ -209,9 +209,9 @@ e1000_autoneg_timer(void *opaque)
     E1000State *s = opaque;
     if (!qemu_get_queue(s->nic)->link_down) {
         e1000_link_up(s);
+        s->phy_reg[PHY_STATUS] |= MII_SR_AUTONEG_COMPLETE;
+        DBGOUT(PHY, "Auto negotiation is completed\n");
     }
-    s->phy_reg[PHY_STATUS] |= MII_SR_AUTONEG_COMPLETE;
-    DBGOUT(PHY, "Auto negotiation is completed\n");
 }
 
 static void (*phyreg_writeops[])(E1000State *, int, uint16_t) = {
@@ -853,7 +853,15 @@ e1000_set_link_status(NetClientState *nc)
     if (nc->link_down) {
         e1000_link_down(s);
     } else {
-        e1000_link_up(s);
+        if (s->phy_reg[PHY_CTRL] & MII_CR_AUTO_NEG_EN &&
+            s->phy_reg[PHY_CTRL] & MII_CR_RESTART_AUTO_NEG &&
+            !(s->phy_reg[PHY_STATUS] & MII_SR_AUTONEG_COMPLETE)) {
+            /* emulate auto-negotiation if supported */
+            timer_mod(s->autoneg_timer,
+                      qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 500);
+        } else {
+            e1000_link_up(s);
+        }
     }
 
     if (s->mac_reg[STATUS] != old_status)
-- 
1.9.3